The objective of this proposal are to study a new organelle of mammalian germ cells termed a dictyosome-like structure (DLS). DLS have been noted in testes of a variety of species but not in other cells and tissues. They bear a distinct resemblance to Golgi apparatus but DLS and Golgi apparatus frequently coexist in the same cell. DLS are composed of stacks of 2-17 saccules. Microtubule-like structures about 100 A in diameter bridge both the inter- and intra-saccular spaces. At least some of the microtubule-like structures appear to be continuous through two or more saccules. The presence of the microtubule-like elements makes the DLS clearly different from Golgi apparatus and places it as a candidate as a new organelle unique to certain stages of spermatogenesis. Because DLS contain distinct microtubule-like elements and appear to carry out some function restricted to requirements unique to late stages of germ cell development in the testis, these structures emerge as potential targets for development of drugs applicable to fertility control in the male. The objectives of this study are to study DLS of testis germ cells to learn: 1) more about their structure, function and dstribution among species, and 2) to what extent DLS contain unique macromolecules (i.e. a unique tubulin-like or tubulin-associated protein) against which specific blocking drugs could be developed. A correlative approach will be emphasized in which information from electron microscopy and cytochemistry will be combined with cell fractionation and biochemical analyses.